ZVS-DSR bilateral feedback converter control method

Abstract

The invention provides a ZVS-DSR bilateral feedback converter control method, which comprises the following steps: when an input unit supplies power, a first switch is closed and a second switch is opened, so that the input current of the input unit is stored in a transformer, the first switch is opened, the second switch is closed, and the current stored in the transformer is transmitted to an output capacitor and an output unit for output. Switching off the input of the input unit and the first switch and switching on the second switch, so that the electric energy in the output capacitor is reversely output to the transformer through the secondary winding; the second switch is switched off to demagnetize the transformer, so that the voltage of the primary winding is reduced, and the mutual inductance voltage of the primary winding or the auxiliary winding is reduced; when the voltage is lower than the first preset voltage or the decline slope reaches the preset slope, the first switch is turned on, so that the first loop valley bottom is turned on or zero voltage is turned on, and corresponding energy is transmitted to the output unit according to the signal time. According to the invention, valley bottom conduction or zero-voltage conduction of the first loop can be realized, and waste of electric energy during conduction of the converter is avoided.

Description

Technical Field

[0001] The present invention relates to the technical field of converters, and in particular to a ZVS-DSR bilateral feedback converter control method. Background Art

[0002] Compared with the traditional optocoupler structure of secondary feedback, the biggest advantage of the primary side feedback architecture (PSR) is that it eliminates these two chips and a set of components that work with them. Therefore, it has a broad market and prospects in the mobile phone charger market. However, the primary side feedback usually has only one output voltage feedback loop, and the change of the secondary side voltage can only be monitored when the secondary side of the transformer is demagnetized. Therefore, the idea of ​​the double-side feedback architecture (DSR) was also proposed, hoping to detect the change of the secondary side voltage through the primary side, so as to realize the control of the secondary side and primary side switch tubes. However, the primary and secondary signal detection of DSR control in actual applications is the biggest problem. Since the signal and transformer waveform share the transformer, it is difficult to solve the signal detection problem in the application. In addition, due to too many functions in DSR, the VCC power supply is insufficient, and the excess energy loss caused by increasing the power supply is a problem. Therefore, how to achieve zero voltage conduction (ZVS) has become an urgent problem to be solved. Summary of the invention In view of this, an object of the present invention is to overcome the deficiencies in the prior art and provide a ZVS-DSR bilateral feedback converter control method.

[0003] The present invention provides the following technical solutions: The present application provides a ZVS-DSR bilateral feedback converter control method, which is applied to a converter, wherein the converter comprises: a primary side, a transformer and a secondary side, wherein the transformer comprises a primary winding and a secondary winding; The primary side includes: an input unit, a first switch and a primary winding, and the secondary side includes: a secondary winding, an output capacitor, a second switch and an output unit; the input unit, the first switch and the primary winding are connected in sequence to form a first loop; the secondary winding, the second switch and the output capacitor are connected in sequence to form a second loop; the output unit is connected to the output capacitor; The method comprises: When the input unit supplies power, the first switch is in a closed state and the second switch is in an open state, so that the input current of the input unit is stored in the transformer, the first switch is opened and the second switch is closed, and the current stored in the transformer is transferred to the output capacitor and the output unit output; Disconnecting the input of the input unit and the first switch, and closing the second switch, so that the electric energy in the output capacitor is outputted to the transformer in reverse through the secondary winding; The second switch is turned off to demagnetize the transformer, thereby reducing the voltage of the primary winding, or an auxiliary winding is added to reduce the mutual inductance voltage of the primary winding or the auxiliary winding; when the voltage is lower than the first preset voltage or the falling slope reaches the preset slope, the first switch is turned on to make the first loop valley-turned on or zero-voltage turned on, and the corresponding energy is transferred to the output unit according to the signal time.

[0004] In one embodiment, the method further comprises: Obtaining an output energy formula of the converter, and determining a switching signal on the secondary side according to the output energy formula; The output energy formula is: 0.5×IPK 2 ×FL; where IPK is the primary peak current, F is the frequency, and L is the transformer inductance. When the primary side establishes the initial operating voltage, the frequency is controlled by the secondary side; The primary side controls the current of the primary side according to the switching signal of the secondary side to form a bilateral feedback.

[0005] In one embodiment, the method further comprises: The primary side uses the closing time of the first loop, or the last reverse time, or the demagnetization time after the second loop is closed as the initial time, obtains the current reverse current conduction time of the second loop, and calculates the time difference between the initial time and the conduction time; The peak current value of the primary side conduction is set according to the time difference, and the setting method is: At least one time period is set, which corresponds to a fixed current within the time period range, and / or the peak current is reduced as the time difference increases within a time period interval.

[0006] In one implementation, the obtaining the current reverse current conduction moment of the second loop includes: Acquire a first voltage waveform of the secondary side, and if the first voltage waveform changes from a resonant waveform to a smooth waveform, acquire a change time, and use the change time as the turn-on time; And / or, obtaining the waveform of the second voltage on the primary side or the secondary side, determining whether the waveform drop speed of the second voltage is greater than a speed threshold, and taking the moment when the drop speed is greater than the speed threshold as the turn-on moment.

[0007] In one implementation, the determining whether the waveform drop speed of the second voltage is greater than a speed threshold includes: Threshold settings are modified based on secondary output requirements and / or the product’s own frequency; If it is greater than the preset slope, it is determined that the speed of the waveform of the second voltage is greater than the speed threshold and is judged to be a DSR signal. The first loop is turned on to transfer matching energy according to its signal time.

[0008] In one implementation, the slope signal capture method corresponding to the slope adopts at least one of the following: voltage change value triggering in a specified time interval, passband capture, RC damping capture, and loop current sudden change capture.

[0009] In one implementation, the converter further includes a fourth switch connected in parallel with the output unit; when the output voltage is higher than a preset value, the output voltage is reduced by at least one of the following methods: Mode 1: Turning on the fourth switch to reduce the output voltage; Method 2: Turn on the second loop and transfer the excess voltage back to the primary side; Method 3: Increase the dummy load to consume the excess voltage.

[0010] In one implementation, the converter further includes a filter capacitor and a third switch, and the filter capacitor is sequentially connected with the output capacitor, the secondary winding and the third switch to form a third loop; the method further includes: Obtaining the voltage difference between the filter capacitor voltage and the output capacitor voltage; According to the voltage difference, power is supplied in at least one of the following ways: Method 1: If the voltage difference is greater than or equal to the preset voltage difference, the second loop is first turned on to store the electric energy in the output capacitor into the transformer, and then the third loop is turned on to supply power to the filter capacitor; Mode 2: If the voltage difference is less than the preset voltage difference, the third loop is turned on, or the third loop and the second loop are turned on alternately to supply power to the filter capacitor.

[0011] In one implementation, in order to avoid the occurrence of common or post-common lossless devices in the control process of the bilateral feedback converter, at least one of the following control methods is adopted: Method 1: Output voltage segmented staggered control; Method 2: After demagnetization is completed, the voltage waveform during the resonance period is segmented and controlled. On one side of the demagnetization completed resonance waveform, there is a secondary control window, and on the other side, there is a primary control window, and a preset gap margin is reserved; Method 3: Timing segment control, divided into at least one timing segment, each timing segment can only be controlled by one side; Method 4: Quickly disconnect when a common problem occurs; Method 5: Take energy absorption when common occurs.

[0012] In one implementation, when the supply voltage on the primary side is insufficient, the supply voltage is increased by at least one of the following methods: Method 1: Increase the primary side supply voltage by increasing the dummy load and the primary side frequency; Method 2: Let the primary side power supply voltage enter sleep mode or hiccup and restart; Method 3: Increase the frequency or current on the primary side. When the energy transferred to the secondary side is too large, it is transferred back to the primary side by increasing the DSR current.

[0013] The embodiments of the present invention have the following beneficial effects: The ZVS-DSR bilateral feedback converter control method provided by the present invention utilizes the demagnetized secondary winding to charge the transformer, and then disconnects the second switch to demagnetize the transformer, so that the first voltage at the connection end of the primary winding and the first switch is reduced; when the first voltage is lower than the first preset voltage, the first switch is turned on to make the first loop valley-bottomed or zero-voltage turned on, thereby avoiding the waste of electric energy when the converter is turned on and ensuring circuit safety.

[0014] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and understandable, preferred embodiments are given below and described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0016] Figure 1 A schematic diagram of the circuit structure of a ZVS-DSR bilateral feedback converter of this embodiment is shown; Figure 2 A schematic flow chart of a ZVS-DSR bilateral feedback converter control method according to the present embodiment is shown; Figure 3 A schematic diagram of a ZVS-DSR bilateral feedback converter control circuit transformation of this embodiment is shown; Figure 4 A schematic diagram of a peak current value setting method of this embodiment is shown; Figure 5 A schematic diagram of waveform change of this embodiment is shown; Figure 6 Another waveform change schematic diagram of this embodiment is shown; Figure 7A schematic diagram of a first filter capacitor power supply according to the present embodiment is shown; Figure 8 A schematic diagram of a second filter capacitor power supply of this embodiment is shown; Fig. 9 A third filter capacitor power supply schematic diagram of this embodiment is shown; Fig.10 A fourth filter capacitor power supply schematic diagram of this embodiment is shown.

[0017] Description of main component symbols: T1, transformer; NP, primary winding; NS, secondary winding; K1, first switch; K2, second switch; K3, third switch; K4, fourth switch; EC1, input capacitor; EC2, output capacitor; EC3, filter capacitor; D1, diode; R1, load resistor. DETAILED DESCRIPTION

[0018] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

[0019] It should be noted that when an element is referred to as being "fixed to" another element, it may be directly on the other element or there may be a central element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. In contrast, when an element is referred to as being "directly on" another element, there is no intermediate element. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are for illustrative purposes only.

[0020] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0021] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0022] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used in the specification of the template herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention. When there is any disagreement in the description of the embodiments, the description of the claims shall prevail. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0023] Example 1 See also Figure 1 , Figure 1 A schematic diagram of the circuit structure of a ZVS-DSR bilateral feedback converter provided in this embodiment, the converter comprises: a primary side, a transformer T1 and a secondary side, the transformer T1 comprises a primary winding NP and a secondary winding NS.

[0024] The primary side includes: an input unit, a first switch K1 and a primary winding NP, and the secondary side includes: a secondary winding NS, an output capacitor EC2, a second switch K2 and an output unit; the input unit, the first switch K1 and the primary winding NP are connected in sequence to form a first loop; the secondary winding NS, the second switch K2 and the output capacitor EC2 are connected in sequence to form a second loop; the output unit is connected to the output capacitor EC2.

[0025] See also Figure 2 , Figure 2 A schematic flow chart of a ZVS-DSR bilateral feedback converter control method provided in this embodiment, the method comprising: S201. When the input unit is powered, the first switch is in a closed state and the second switch is in an open state, so that the input current of the input unit is stored in the transformer, the first switch is opened and the second switch is closed, and the current stored in the transformer is transferred to the output capacitor and the output unit output.

[0026] S202 . Disconnect the input of the input unit and the first switch, and close the second switch, so that the electric energy in the output capacitor is output in reverse to the transformer through the secondary winding.

[0027] See also Figure 3 , Figure 3 A schematic diagram of a ZVS-DSR bilateral feedback converter control circuit transformation provided in this embodiment.

[0028] Specifically, when the ZVS-DSR bilateral feedback converter control circuit is in normal operation, its state is as follows: Figure 3 As shown in a in FIG. 1 , the input unit can store energy in the transformer T1. When the first switch K1 is disconnected, the state of the control circuit is as follows: Figure 3 b and Figure 3 As shown in c, at this time, the input unit no longer supplies power to the transformer T1, and the second switch K2 is closed, so that the electric energy in the secondary side output capacitor EC2 is reversely output to the transformer T1 through the secondary winding NS.

[0029] S203, disconnecting the second switch to demagnetize the transformer, thereby reducing the voltage of the primary winding, or adding an auxiliary winding to reduce the mutual inductance voltage of the primary winding or the auxiliary winding; when the voltage is lower than the first preset voltage or the falling slope reaches the preset slope, the first switch is turned on to make the first loop valley-turned on or zero-voltage turned on, and transfer corresponding energy to the output unit according to the signal time.

[0030] When the electric energy of the output capacitor EC2 is input to the transformer T1, the second switch K2 is disconnected. Figure 3 As shown in d, at this time, since the electric energy in the secondary side output capacitor EC2 can no longer be reversely output to the transformer T1 through the secondary winding NS, the transformer T1 begins to demagnetize, and the first voltage at the connection end of the primary winding NP and the first switch K1 decreases. When the first voltage is lower than the first preset voltage, the first switch K1 is controlled to be turned on, thereby realizing the first loop, that is, the valley conduction or zero voltage conduction of the primary side circuit. Thereby reducing the loss of the switch junction capacitance and the transformer T1 junction capacitance, wherein the saved junction capacitance loss is: 0.5*C*V*V*F, wherein C is the junction capacitance of the switch tube and the transformer T1, V is the voltage across the switch tube, and F is the frequency.

[0031] In one embodiment, the method further comprises: Obtaining an output energy formula of the converter, and determining a switching signal on the secondary side according to the output energy formula;

[0032] The output energy formula is: 0.5×IPK 2 ×FL; where IPK is the primary peak current, F is the frequency, and L is the transformer inductance. When the primary side establishes the initial operating voltage, the frequency is controlled by the secondary side; The primary side controls the current of the primary side according to the switching signal of the secondary side to form a bilateral feedback.

[0033] According to the output energy formula, the primary can be used as a signal based on the secondary switch to control the primary current to form DSR bilateral feedback, thereby achieving de-optocoupling to meet different output requirements, including variable voltage output, forming a new ZVS-DSR bilateral feedback circuit.

[0034] See also Figure 4 , the ZVS-DSR bilateral feedback converter control method further includes: S301. The primary side uses the closing time of the first loop, or the last reverse time, or the demagnetization time after the second loop is closed as the initial moment, obtains the current reverse current conduction moment of the second loop, and calculates the time difference between the initial moment and the conduction moment.

[0035] Specifically, the second loop can realize at least two of the following functions at the same time: synchronous rectification can be realized during demagnetization. And, after demagnetization, it continues to conduct to realize reverse backflow current to realize primary valley or zero voltage soft switching. The reverse conduction time of the second loop is defined according to the output requirements to transmit the secondary signal; it can replace the dummy load to reduce the output excess energy and discharge it to the primary; and it can realize the bidirectional conduction function of output to input power supply according to the requirements of both sides.

[0036] S302, setting the peak current value of the primary side conduction according to the time difference, wherein the setting method is: setting at least one time period, which corresponds to a fixed current within the time period range, and / or reducing the peak current within a time period interval as the time difference increases.

[0037] This embodiment replaces the high and low feedback voltage of the optocoupler with the length of the timing, thereby realizing the feedback signal from the secondary side to the primary side, and the secondary feedback time directly corresponds to or dynamically controls the current of the primary conduction, thereby realizing energy balance transfer.

[0038] See also Figure 5 , Figure 5 A schematic diagram of waveform changes provided in this embodiment.

[0039] in, Figure 5 a in the figure is the voltage waveform of the switch tube or transformer in the discontinuous mode. Figure 5 Figure b is the waveform of the current in the transformer in discontinuous mode.

[0040] In one implementation, the obtaining the current reverse current conduction moment of the second loop includes: The first voltage waveform of the secondary side is obtained. If the first voltage waveform changes from a resonant waveform to a flat waveform, a change time is obtained and the change time is used as the turn-on time.

[0041] See also Figure 6 , Figure 6 Another waveform change schematic diagram provided for this embodiment.

[0042] in, Figure 6 a in the figure is the voltage waveform of the switch tube or transformer in critical mode. Figure 6 Figure b is the waveform of the current in the transformer under critical mode.

[0043] And / or, obtaining the waveform of the second voltage on the primary side or the secondary side, determining whether the waveform drop speed of the second voltage is greater than a speed threshold, and taking the moment when the drop speed is greater than the speed threshold as the turn-on moment.

[0044] like Figure 5 As shown in FIG. 1 , when zero voltage conduction is not achieved on the primary side, the voltage waveform detected on the primary side is a resonant waveform. After zero voltage conduction is achieved on the primary side, its voltage waveform is converted into a flat waveform. Therefore, the moment of voltage waveform conversion is the moment of zero voltage conduction on the primary side.

[0045] Or, if Figure 6 As shown, when the primary side does not achieve zero voltage conduction, the voltage waveform detected by the primary side is in a steady decreasing state. When it is zero voltage conduction, the voltage waveform will drop rapidly. Therefore, the decreasing speed of the voltage waveform at each moment can be obtained, and it can be determined whether the decreasing speed at each moment is greater than the speed threshold. If it is greater than the speed threshold, it means that the primary side has achieved zero voltage conduction.

[0046] In one implementation, the determining whether the waveform drop speed of the second voltage is greater than a speed threshold comprises: Threshold settings are modified based on secondary output requirements and / or the product’s own frequency; If it is greater than the preset slope, it is determined that the speed of the waveform of the second voltage is greater than the speed threshold and is judged to be a DSR signal. The first loop is turned on to transfer matching energy according to its signal time.

[0047] Among them, the demand for the secondary side load can also be judged based on the zero voltage conduction signal, which is used as a timing signal to judge the load demand on the secondary side. If zero voltage conduction is achieved immediately after demagnetization is completed, it means that the secondary side needs maximum energy supply. If the zero voltage conduction signal is not seen until a long time after demagnetization is completed, it means that the secondary energy demand is not large.

[0048] The difference in the primary resonance slope formed after the secondary side is turned on can be used to determine whether it is a secondary feedback signal. The slope can be directly captured by the slope integration method or the automatic trigger holding method, in which the automatic trigger holding adopts the existing voltage capacitor holding, oscillation produces a pressure difference, the pressure difference enters the capacitor holding through the diode D1 and triggers the comparator, and resets to control.

[0049] Specifically, the turn-on time is determined by obtaining the falling speed of the primary side voltage waveform at each moment, or the changing state of the voltage waveform in real time. Since the turn-on time is determined by calculating the waveform characteristics or the falling speed, there will be a certain delay, that is, hysteresis. By obtaining the slope of the voltage waveform, the zero voltage turn-on time of the primary side can be better captured.

[0050] Among them, the slope signal capture method corresponding to the slope adopts at least one of the following: voltage change value triggering in a specified time interval, passband capture, RC damping capture and loop current sudden change capture.

[0051] In one implementation, obtaining the slope of the second waveform includes: The slope of the second waveform is obtained by a slope calculation formula, and the slope calculation formula is: K=△V / △T, K is the slope, △V is the voltage change, △T is the time change; Among them, V=△I*L / △T, △I is the Ipk current on transformer T1, and L is the inductance of transformer T1.

[0052] Specifically, the voltage during the △T change time can be equivalent to the slope K. Since L is fixed in a transformer T1, it can be simplified to only consider △I, that is, Ipk current to distinguish different signal values. Usually, the reverse current needs to be greater than the current of self-resonance after the secondary side demagnetization is completed. Similarly, the secondary side detects whether the energy on the primary side is transferred by the primary side, or whether the secondary side generates reverse energy by itself, and this is also used to judge.

[0053] The formula is further transformed into V△T =△I*L. The V△T integral can be used to distinguish the energy transmitted on the primary side and the secondary DSR signal. The slope judgment method of the above transformation method can effectively eliminate the interference of noise, and at the same time, it can truly realize the transmission and reception of signals in any time period.

[0054] See also Figure 7 , Figure 7 This is a schematic diagram of power supply of the first filter capacitor EC3 provided in this embodiment.

[0055] The converter further includes a filter capacitor EC3, wherein the filter capacitor EC3 is connected in sequence with the output capacitor EC2, the secondary winding NS and the second switch K2 to form a third loop; the method further includes: Obtain the voltage difference between the filter capacitor EC3 voltage and the output capacitor EC2 voltage; If the voltage difference is greater than or equal to the preset voltage difference, the second loop is first turned on to store the electric energy in the output capacitor EC2 into the transformer T1, and then the third loop is turned on to supply power to the filter capacitor EC3.

[0056] See also Figure 8 and Fig. 9 , Figure 8 and Fig. 9 Schematic diagram of power supply of two other filter capacitors EC3 provided in this embodiment.

[0057] Specifically, when the second switch K2 is closed, the first switch K1 is opened, and the output unit is no longer powered. At this time, the third loop is turned on to form a closed loop, and the electric energy of the output capacitor EC2 will power the filter capacitor EC3 through the second switch K2.

[0058] If the voltage difference is greater than or equal to the preset voltage difference, that is, the voltage of the filter capacitor EC3 is higher than the voltage of the output capacitor EC2, or the voltage difference between the two is small, if normal power supply is adopted, it will take a long time to introduce the electric energy of the output capacitor EC2 into the secondary winding NS of the transformer T1, and then introduce it into the filter capacitor EC3 through the secondary winding NS. At this time, the second loop can be turned on first to store the electric energy in the output capacitor EC2 into the transformer T1, and then the third loop can be turned on to realize low power consumption boost to supply power to the filter capacitor EC3.

[0059] Among them, an input capacitor EC1 can also be set on the primary side, and the input capacitor EC1 is connected in parallel with the input unit. A diode D1 and a load resistor R1 can also be set on the secondary side. The positive electrode of the diode D1 is connected to the secondary winding NS, and the negative electrode of the diode D1 is connected to the load resistor R1. The load resistor R1 is connected to the filter capacitor EC3 through the third switch K3.

[0060] The filter capacitor, the output capacitor, the secondary winding and the third switch are sequentially connected to form a third loop; the method further includes: Obtaining the voltage difference between the filter capacitor voltage and the output capacitor voltage; According to the voltage difference, power is supplied in at least one of the following ways: Method 1: If the voltage difference is greater than or equal to the preset voltage difference, the second loop is first turned on to store the electric energy in the output capacitor into the transformer, and then the third loop is turned on to supply power to the filter capacitor; Mode 2: If the voltage difference is less than the preset voltage difference, the third loop is turned on, or the third loop and the second loop are turned on alternately to supply power to the filter capacitor.

[0061] In one implementation, if the voltage difference is less than a preset voltage difference, the third loop can be directly turned on, or the third loop and the second loop can be turned on alternately, and the transformer T1 can be used to step down and boost the voltage to supply power to the filter capacitor EC3.

[0062] Alternatively, the mutual inductance voltage of the first loop or the leakage inductance voltage of the second loop is used to power the filter capacitor EC3.

[0063] In one embodiment, see Figure 7-Figure 9 , you can Figure 7-Figure 9 The output unit in is regarded as the first output unit, and a second output unit is set on the side of the filter capacitor EC3, then the voltage conversion of the ZVS-DSR bilateral feedback converter can be divided into two aspects.

[0064] First, when hour, V o1 , V o2 are the voltage of the first output unit and the voltage of the second output unit respectively.

[0065] Step-down power supply: In phase 1, the first output unit stores energy in the transformer, and the current in the second loop increases in the opposite direction. Assume that the duration of phase 1 is T1 and the duration of phase 2 is T2. At the end of phase 1, the secondary side current is , n is the turns ratio between the primary and secondary sides of the transformer, is the magnetizing inductance, in stage 2, i s Continue to increase in the reverse direction. At the end of stage 2, the secondary current is Among them, stage 1 is the power supply stage when the second loop is closed, and stage 2 is the power supply stage when the third loop is closed.

[0066] 2. When hour.

[0067] Boost power supply: In phase 1, the first output unit charges the transformer and the energy is stored in the transformer. At the end of phase 1, the secondary side current is In stage 2, the energy stored in the first output unit and the transformer in stage 1 together provide energy for the second output, and the secondary current increases. At the end of stage 2, the secondary current is .

[0068] From this, the current and power expressions of the dual output can be obtained as follows:

[0069]

[0070]

[0071]

[0072] In the formula, I o1 , Po1 , I o2 , P o2 They represent the first output current, the first output power, the second output current, and the second output power respectively. I peak is the peak current of the primary side, T s is the demagnetization time of the secondary side, T For the working cycle.

[0073] In one embodiment, see Fig.10 The converter further includes a fourth switch K4, which is connected in parallel with the output unit; when the output voltage is higher than a preset value, the output voltage is reduced by at least one of the following methods: Mode 1: Turning on the fourth switch to reduce the output voltage; Method 2: Turn on the second loop and transfer the excess voltage back to the primary side; Method 3: Increase the dummy load to consume the excess voltage.

[0074] In one implementation, in order to avoid the occurrence of common or post-common lossless devices in the control process of the bilateral feedback converter, at least one of the following control methods is adopted: Method 1: Output voltage segmented staggered control; Method 2: After demagnetization is completed, the voltage waveform during the resonance period is segmented and controlled. On one side of the demagnetization completed resonance waveform, there is a secondary control window, and on the other side, there is a primary control window, and a preset gap margin is reserved; Method 3: Timing segment control, divided into at least one timing segment, each timing segment can only be controlled by one side; Method 4: Quickly disconnect when a common problem occurs; Method 5: Take energy absorption when common occurs.

[0075] In one implementation, when the supply voltage on the primary side is insufficient, the supply voltage is increased by at least one of the following methods: Method 1: Increase the primary side supply voltage by increasing the dummy load and the primary side frequency; Method 2: Let the primary side power supply voltage enter sleep mode or hiccup and restart; Method 3: Increase the frequency or current on the primary side. When the energy transferred to the secondary side is too large, it is transferred back to the primary side by increasing the DSR current.

[0076] In one implementation, this embodiment uses at least one of the following methods to prevent secondary communication from causing a crash: Method 1: During the resonance period after demagnetization is completed, the offset voltage is turned on: the second loop is turned on to feedback the secondary signal only when the resonance voltage is above zero, and the first loop is turned on on the primary side only during the valley period above zero voltage.

[0077] Method 2: stagger the period of the secondary feedback signal: for example, the resonance period and / or the period when the resonance is almost completed is left for the second loop to be turned on; after a preset period of time, no signal feedback is performed. At this time, if the primary side sets a maximum time without receiving the secondary side signal, it will turn on itself for detection.

[0078] Method 3: Voltage segment control, setting the reference voltage V1 on the primary side. Before there is a ZVS feedback signal on the secondary side, the primary side controls the converter according to the PSR primary feedback mode.

[0079] Two reference voltages V2 and base voltage V3 are set on the secondary side, where V3 voltage is higher than V2 voltage. Before V2 voltage is reached, no ZVS-DSR signal is fed back to prevent commonality with the primary side. After V2 is reached, the second loop is turned on to feed back the ZVS-DSR signal according to the output unit requirements. When V3 is reached, the frequency is reduced or the feedback is turned off.

[0080] Method 4: The primary side and / or the secondary side have a common protection detection function, and once detected, they are shut down quickly.

[0081] In one embodiment, the converter can be selected as either a dual-winding or a triple-winding; the main control periphery is equipped with an EC2 capacitor or the input is directly powered; the output control can also be directly powered or equipped with a separate external capacitor; a voltage divider detection resistor is led out from the transformer T1 winding to the inside of the chip to detect the output signal by voltage division. When three windings are used, the voltage divider detection resistor can also be integrated into the inside; the output voltage detection can be external or integrated into the chip; the secondary control chip can also integrate or externalize the reverse current size adjustment pin; the output primary chip can integrate or externalize the load voltage and current adjustment pin.

[0082] The ZVS-DSR converter can replace or add different components according to actual functional requirements: the diode D1 in the ZVS-DSR converter can be replaced with a switch tube; the first switch K1 can use a triode, a MOS tube or a gallium nitride and Darlington tube; EMC components and / or a multi-channel output module can be electrically connected in the converter; the third loop can add components such as a diode D1 and a resistor according to the function.

[0083] The type of the input unit includes at least one of the following: AC rectifier input, DC input, fluctuating voltage input, capacitor and battery.

[0084] The output unit includes at least one output, wherein the at least one output includes but is not limited to: a resistive load, a capacitive load, a motor, an LED lamp, other electronic equipment, etc.

[0085] In all examples shown and described herein, any specific values ​​should be interpreted as merely exemplary and not as limiting, and thus other examples of the exemplary embodiments may have different values.

[0086] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0087] The above-mentioned embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the present invention. It should be pointed out that for ordinary technicians in this field, several modifications and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention.

Claims

1. A ZVS-DSR bilateral feedback converter control method, applied to a converter, characterized in that: The converter comprises: a primary side, a transformer and a secondary side, wherein the transformer comprises a primary winding and a secondary winding; The primary side includes: an input unit, a first switch and a primary winding, and the secondary side includes: a secondary winding, an output capacitor, a second switch and an output unit; the input unit, the first switch and the primary winding are connected in sequence to form a first loop; the secondary winding, the second switch and the output capacitor are connected in sequence to form a second loop; the output unit is connected to the output capacitor; The method comprises: When the input unit supplies power, the first switch is in a closed state and the second switch is in an open state, so that the input current of the input unit is stored in the transformer, the first switch is opened and the second switch is closed, and the current stored in the transformer is transferred to the output capacitor and the output unit output; Disconnecting the input of the input unit and the first switch, and closing the second switch, so that the electric energy in the output capacitor is outputted to the transformer in reverse through the secondary winding; The second switch is turned off to demagnetize the transformer, thereby reducing the voltage of the primary winding, or an auxiliary winding is added to reduce the mutual inductance voltage of the primary winding or the auxiliary winding; when the voltage is lower than the first preset voltage or the falling slope reaches the preset slope, the first switch is turned on to make the first loop valley-turned on or zero-voltage turned on, and the corresponding energy is transferred to the output unit according to the signal time.

2. The ZVS-DSR bilateral feedback converter control method according to claim 1, characterized in that: The method further comprises: Obtaining an output energy formula of the converter, and determining a switching signal on the secondary side according to the output energy formula; The output energy formula is: 0.5×IPK 2 ×FL; where IPK is the primary peak current, F is the frequency, and L is the transformer inductance. When the primary side establishes the initial operating voltage, the frequency is controlled by the secondary side; The primary side controls the current of the primary side according to the switching signal of the secondary side to form a bilateral feedback.

3. The ZVS-DSR bilateral feedback converter control method according to claim 1, characterized in that: The method further comprises: The primary side uses the closing time of the first loop, or the last reverse time, or the demagnetization time after the second loop is closed as the initial time, obtains the current reverse current conduction time of the second loop, and calculates the time difference between the initial time and the conduction time; The peak current value of the primary side conduction is set according to the time difference, and the setting method is: At least one time period is set, which corresponds to a fixed current within the time period range, and / or the peak current is reduced as the time difference increases within a time period interval.

4. The ZVS-DSR bilateral feedback converter control method according to claim 3, characterized in that: The obtaining the current reverse current conduction moment of the second loop includes: Acquire a first voltage waveform of the secondary side, and if the first voltage waveform changes from a resonant waveform to a smooth waveform, acquire a change time, and use the change time as the turn-on time; And / or, obtaining the waveform of the second voltage on the primary side or the secondary side, determining whether the waveform drop speed of the second voltage is greater than a speed threshold, and taking the moment when the drop speed is greater than the speed threshold as the turn-on moment.

5. The ZVS-DSR bilateral feedback converter control method according to claim 4, characterized in that: The determining whether the waveform drop speed of the second voltage is greater than a speed threshold comprises: Threshold settings are modified based on secondary output requirements and / or the product’s own frequency; If it is greater than the preset slope, it is determined that the speed of the waveform of the second voltage is greater than the speed threshold and is judged to be a DSR signal. The first loop is turned on to transfer matching energy according to its signal time.

6. The ZVS-DSR bilateral feedback converter control method according to claim 5, characterized in that: The slope signal capture method corresponding to the slope adopts at least one of the following: voltage change value triggering in a specified time interval, passband capture, RC damping capture and loop current sudden change capture.

7. The ZVS-DSR bilateral feedback converter control method according to claim 1, characterized in that: The converter further includes a fourth switch connected in parallel with the output unit; when the output voltage is higher than a preset value, the output voltage is reduced by at least one of the following methods: Mode 1: Turning on the fourth switch to reduce the output voltage; Method 2: Turn on the second loop and transfer the excess voltage back to the primary side; Method 3: Increase the dummy load to consume the excess voltage.

8. The ZVS-DSR bilateral feedback converter control method according to claim 1, characterized in that: The converter further includes a filter capacitor and a third switch, wherein the filter capacitor is connected in sequence with the output capacitor, the secondary winding and the third switch to form a third loop; the method further includes: Obtaining the voltage difference between the filter capacitor voltage and the output capacitor voltage; According to the voltage difference, power is supplied in at least one of the following ways: Method 1: If the voltage difference is greater than or equal to the preset voltage difference, the second loop is first turned on to store the electric energy in the output capacitor into the transformer, and then the third loop is turned on to supply power to the filter capacitor; Mode 2: If the voltage difference is less than the preset voltage difference, the third loop is turned on, or the third loop and the second loop are turned on alternately to supply power to the filter capacitor.

9. The ZVS-DSR bilateral feedback converter control method according to claim 8, characterized in that: When a common problem occurs during the control process of the bilateral feedback converter, at least one of the following control methods is adopted: Method 1: Output voltage segmented staggered control; Method 2: After demagnetization is completed, the voltage waveform during the resonance period is segmented and controlled. On one side of the demagnetization completed resonance waveform, there is a secondary control window, and on the other side, there is a primary control window, and a preset gap margin is reserved; Method 3: Timing segment control, divided into at least one timing segment, each timing segment can only be controlled by one side; Method 4: Quickly disconnect when a common problem occurs; Method 5: Take energy absorption when common occurs.

10. The ZVS-DSR bilateral feedback converter control method according to claim 1, characterized in that: When the supply voltage on the primary side is insufficient, use at least one of the following methods to increase the supply voltage: Method 1: Increase the primary side supply voltage by increasing the dummy load and the primary side frequency; Method 2: Let the primary side power supply voltage enter sleep mode or hiccup and restart; Method 3: Increase the frequency or current on the primary side. When the energy transferred to the secondary side is too large, it is transferred back to the primary side by increasing the DSR current.

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